Liquid crystal display elements have been used in clocks, electronic calculators, various home appliances, measurement machines, panels for automobiles, word processors, electronic personal organizers, printers, computers, TVs, and the like. Representative examples of a liquid crystal display method include TN (twisted nematic) type, STN (super-twisted nematic) type, DS (dynamic light scattering) type, GH (guest-host) type, IPS (in-plane switching) type, OCB (optically compensated birefringence) type, ECB (electrically controlled birefringence) type, VA (vertical alignment) type, CSH (color super-homeotropic) type, and FLC (ferroelectric liquid crystal) type. Examples of a method for driving the liquid crystal display element include static driving, multiplex driving, a simple matrix method, and an active-matrix (AM) method in which a liquid crystal display element is driven using a TFT (thin-film transistor), a TFD (thin-film diode), or the like.
Among the display methods described above, for example, in an IPS-type display method, an ECB-type display method, a VA-type display method, and a CSH-type display method, a liquid crystal material having a negative Δ∈ is used. Among these display methods, in particular, a VA-type display method in which a liquid crystal display element is driven by AM driving has been employed by display elements that require a high speed and a wide viewing angle, such as TVs.
A nematic liquid crystal composition required for a VA-type display method or the like requires low-voltage driving, a high-speed response, and a wide operating temperature range. In other words, such a nematic liquid crystal composition requires a negative Δ∈, the absolute value of Δ∈ being large, a low viscosity, and a high nematic phase-isotropic liquid phase transition temperature (Tni). In addition, due to the configuration of the product Δn×d of refractive index anisotropy (Δn) and cell gap (d), it is necessary to control the Δn of a liquid crystal material to be within an appropriate range in accordance with cell gap. Furthermore, in the case where the liquid crystal display element is used in TVs or the like, primary importance is placed on a high-speed response capability. Therefore, a liquid crystal material having a low viscosity (η) is anticipated.
Hitherto, various studies of compounds having a negative Δ∈, the absolute value of Δ∈ being large, have been conducted in order to improve the characteristics of a liquid crystal composition.
The following liquid crystal composition that includes the liquid crystal compounds (A) and (B) having a 2,3-difluorophenylene skeleton (see PTL 1) has been disclosed as a liquid crystal material having a negative Δ∈.

This liquid crystal composition includes liquid crystal compounds (C) and (D) having a Δ∈ of substantially zero. However, the viscosity of the liquid crystal composition has not yet been reduced to a sufficiently low level appropriate for a liquid crystal composition that requires a high-speed response suitable for liquid crystal TVs or the like.

A liquid crystal composition that includes the compound represented by Formula (E) has also been disclosed. However, this liquid crystal composition (see PTL 3) includes a low-Δn liquid crystal composition (see PTL 2) that includes the above-described liquid crystal compound (D) and, in order to increase response speed, a compound (alkenyl compound) having an alkenyl group in the molecule, such as the liquid crystal compound (F). Thus, further studies are needed in order to achieve a high Δn and high reliability.

A liquid crystal composition that includes the compound represented by Formula (G) has been disclosed (see PTL 4). Since this liquid crystal composition also includes a compound including an alkenyl compound, such as the liquid crystal compound (F) described above, a faulty display such as burn-in or display unevenness is likely to occur.

The impact of a liquid crystal composition that includes an alkenyl compound on a faulty display has been disclosed (see PTL 5). On the other hand, generally, a reduction in the content of an alkenyl compound in a liquid crystal composition increases the η of the liquid crystal composition, which makes it difficult to realize a high-speed response. Thus, it has been difficult to reduce the risk of a faulty display and achieves a high-speed response.
As described above, it has been difficult to develop a liquid crystal composition having a negative Δ∈0 which allows a high Δn and a low η to be achieved and which eliminates or reduces the risk of a faulty display only by using a compound having a negative Δ∈ and liquid crystal compounds (C), (D), and (F) in combination.
A liquid crystal composition that includes the compound represented by Formula (A), the compound represented by Formula (G), and the compound represented by Formula (III-F31) having a Δ∈ of substantially zero (see PTL 6) is disclosed. However, the content of the compound represented by Formula (III-F31) in this liquid crystal composition is limited because it has been considered impossible to increase the content of a compound having a low vapor pressure since such a compound is volatile under the extremely low pressure generated when a liquid crystal composition is injected into liquid crystal cells during the process of manufacturing a liquid crystal display element. Thus, this liquid crystal composition is disadvantageous in that it has a significantly high viscosity while having a high Δn.

In PTLs 6 and 7, there has already been disclosed a liquid crystal composition that includes a compound having a fluorine-substituted terphenyl structure.
In PTL 8, there has been disclosed a method for improving the response speed of homeotropic liquid crystal cells by using a liquid crystal material whose index expressed by (Formula 1) is large. However, the effect of the method is not ideal.[Math. 1]FoM=K33·Δn2/γ1  (Formula 1)                K33: elastic constant        Δn: refractive index anisotropy        γ1: rotational viscosity        
Accordingly, it has been required for a liquid crystal composition used for producing liquid crystal TVs or the like, which requires a high-speed response, to reduce viscosity (η) and rotational viscosity (γ1) to be sufficiently low and increase elastic constant (K33) to be high without reducing refractive index anisotropy (Δn) or nematic phase-isotropic liquid phase transition temperature (Tni).